Comparison of anti-atopic dermatitis activities between DHMEQ and tacrolimus ointments in mouse model without stratum corneum

Abstract

This study is aimed to further investigate the anti-atopic dermatitis (AD) activities of dehydroxymethylepoxyquinomicin (DHMEQ) ointment and compare its effect with that of tacrolimus ointment based on the previous study that DHMEQ improves AD-like lesions. AD were induced by 2,4-dinitroclilorobenzene/oxazolone (DNCB/OX) repeatedly on the ears of BABL/C mice while medical tape was additionally used to disrupt stratum corneum in order to exacerbate the lesions. The mice were randomly divided into groups, which are normal, vehicle, DHMEQ (0.1%) and tacrolimus (0.1%). Those in the last two groups were externally applied with DHMEQ ointment and tacrolimus ointment, respectively. The results showed that both of them significantly improved dermatitis symptoms of DNCB/OX-induced AD-like lesions, such as redness, itching, weeping, scaling and thickening of the skin, while reducing epidermis thickness, dermis thickness and the number of mast cells as well, which were examined histopathologically. In contrast with DHMEQ, tacrolimus led to a significant decrease in body weight after long-term application. Both DHMEQ and tacrolimus suppress DNCB-induced increase of serum total IgE and attenuate expression of inflammatory factors IL-4, IL-6, IL-13, IL-1β and interferon (IFN)-γ in the disrupted ear tissues. On the other hand, the mice applied with tacrolimus became obviously irritable, jumping up and down, and inflammatory exudation on the lesioned-skin surface of the mice was remarkably observed. Contrary to the side effects made by tacrolimus, DHMEQ didn't cause any adverse stimulus response. As a conclusion, DHMEQ is safer, milder and more suitable for long-term use than tacrolimus for the treatment of AD-like lesions.